Ribbons of the type used in typewriters and similar print mechanisms comprise a web of synthetic resinous material coated with an ink coating which contains, among other things, oil and the material deposited on paper during the printing process. Such print ribbons, especially those of narrow width, may present problems in being driven by the printer mechanism. For example, if oil is exuded from a ribbon onto the feed mechanism, when the ribbon is fed, the presence of the oil can cause hang-up of the film and drag of the film so that the ribbon will not pull through the feed mechanism. In addition, if oil is present on the drive gear, it can have a lubricating effect and cause slippage of the ribbon so that the ribbon will not advance.
In another problem situation, oil can build up on the drive gear to such a thickness that the ribbon will bind on the drive gear. Also, as the ribbon is wound up, the front surface comes into contact with the rear surface, and the presence of oil on the rear surface can adversely affect winding and the ribbon may slip. These problems may be magnified by heat.
The present invention substantially eliminates these problems in a novel typewriter ribbon which, among other things, includes a back coating of such a nature that it alters the friction characteristics of the ribbon and adsorbs oil.